In recent years, the use of light-emitting diodes (LEDs) in development of light fixtures for various common lighting purposes has increased, and this trend has accelerated as advances have been made in the field. Indeed, lighting applications which previously had typically been served by fixtures using what are known as high-intensity discharge (HID) lamps are now being served by LED light fixtures. Such lighting applications include, among a good many others, roadway lighting, factory lighting, parking lot lighting, and commercial building lighting.
There has been a continuous effort made to develop LED lenses for directing LED light into a desired light distribution. Some of such lenses are difficult and expensive to manufacture, which increases overall cost for LED lighting using such lenses. LED lenses often have a large difference between the thickness of the lens along the light-emission axis and the thickness of the lens along its peripheral edges.
Such lenses have been manufactured by using various multi-layer injection molding processes. FIG. 43 illustrates one example of present technology for such processes which utilizes multiple injection units, multiple mold halves, and mechanical transfer of mold components by moving the entire core side of the mold to the next cavity for the next shot. Such multi-layer injection molding requires the use of expensive rotary platens or shuttle systems along with multiple core halves to build up the molded component in layers.
Current systems for the multi-step injection molding process also require parts to be demolded and cooled before being replaced into a cavity for the subsequent shot. Such methods require addition of certain features on the plastic component to facilitate location indexing of the parts in the mold for proper alignment. These added features increase tooling costs and material consumption.
It is desirable to minimize the capital cost of the equipment used in multilayer injection molding, as well as to maximize floor space usage in manufacturing facilities.